During the grinding step of the non-patterned surface of a semiconductor wafer in a manufacturing process of semiconductor devices from a semiconductor wafer, a semiconductor wafer surface protection sheet is attached to the patterned surface of the semiconductor wafer in order to prevent possible damage to the patterned surface.
The patterned surface of a semiconductor wafer has irregularities that include not only circuits, but also relatively high differences in level such as semiconductor bumps. Thus, when attaching a semiconductor wafer surface protection sheet to the semiconductor wafer, creation of voids between the semiconductor wafer surface protection sheet and the irregularity on the patterned surface of the semiconductor wafer results in a uneven distribution of stress across the surface of the semiconductor wafer upon grinding of its non-patterned surface, making the semiconductor wafer liable to breakage. To avoid this problem, semiconductor wafer surface protection sheets have been proposed that can well adjust to surface irregularities.
For example, Patent Literature 1 proposes a semiconductor wafer surface protection sheet made of particular elastomer composition. Patent Literatures 2 and 3 proposes a semiconductor wafer surface protection sheet that includes a base layer, an irregularity absorbing layer, and an adhesive layer.